[v1] idpf: nullify pointers after they are freed

[PATCH] idpf: nullify pointers after they are freed

Posted by Li Li 2 weeks, 1 day ago

rss_data->rss_key and vport->q_vector_idxs need to be nullified after
they are freed. Checks like "if (!rss_data->rss_key)" and
"if (!vport->q_vector_idxs)" in the code could fail if they are not
nullified.

Tested: built and booted the kernel.

Fixes: 83f38f210b85 ("idpf: Fix RSS LUT NULL pointer crash on early ethtool operations")
Fixes: 8a558cbda51b ("idpf: fix potential memory leak on kcalloc() failure")
Signed-off-by: Li Li <boolli@google.com>
---
 drivers/net/ethernet/intel/idpf/idpf_lib.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
index 131a8121839bd..7af4214ec44de 100644
--- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
+++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
@@ -1308,8 +1308,10 @@ static struct idpf_vport *idpf_vport_alloc(struct idpf_adapter *adapter,
 
 free_rss_key:
 	kfree(rss_data->rss_key);
+	rss_data->rss_key = NULL;
 free_vector_idxs:
 	kfree(vport->q_vector_idxs);
+	vport->q_vector_idxs = NULL;
 free_vport:
 	kfree(vport);
 
-- 
2.52.0.457.g6b5491de43-goog

Re: [PATCH] idpf: nullify pointers after they are freed

Posted by Eric Dumazet 2 weeks, 1 day ago

On Fri, Jan 23, 2026 at 6:27 AM Li Li <boolli@google.com> wrote:
>
> rss_data->rss_key and vport->q_vector_idxs need to be nullified after
> they are freed. Checks like "if (!rss_data->rss_key)" and
> "if (!vport->q_vector_idxs)" in the code could fail if they are not
> nullified.
>
> Tested: built and booted the kernel.
>
> Fixes: 83f38f210b85 ("idpf: Fix RSS LUT NULL pointer crash on early ethtool operations")
> Fixes: 8a558cbda51b ("idpf: fix potential memory leak on kcalloc() failure")
> Signed-off-by: Li Li <boolli@google.com>
> ---
>  drivers/net/ethernet/intel/idpf/idpf_lib.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> index 131a8121839bd..7af4214ec44de 100644
> --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> @@ -1308,8 +1308,10 @@ static struct idpf_vport *idpf_vport_alloc(struct idpf_adapter *adapter,
>
>  free_rss_key:
>         kfree(rss_data->rss_key);
> +       rss_data->rss_key = NULL;
>  free_vector_idxs:
>         kfree(vport->q_vector_idxs);
> +       vport->q_vector_idxs = NULL;

vport is freed right after this line.

vport->q_vector_idxs content is not relevant.

If anything tries to deref vport->any_field ater at this point, there
is another bug. KASAN might help.

>  free_vport:
>         kfree(vport);
>
> --
> 2.52.0.457.g6b5491de43-goog
>

Re: [PATCH] idpf: nullify pointers after they are freed

Posted by Li Li 2 weeks ago

On Fri, Jan 23, 2026 at 1:19 AM Eric Dumazet <edumazet@google.com> wrote:
>
> On Fri, Jan 23, 2026 at 6:27 AM Li Li <boolli@google.com> wrote:
> >
> > rss_data->rss_key and vport->q_vector_idxs need to be nullified after
> > they are freed. Checks like "if (!rss_data->rss_key)" and
> > "if (!vport->q_vector_idxs)" in the code could fail if they are not
> > nullified.
> >
> > Tested: built and booted the kernel.
> >
> > Fixes: 83f38f210b85 ("idpf: Fix RSS LUT NULL pointer crash on early ethtool operations")
> > Fixes: 8a558cbda51b ("idpf: fix potential memory leak on kcalloc() failure")
> > Signed-off-by: Li Li <boolli@google.com>
> > ---
> >  drivers/net/ethernet/intel/idpf/idpf_lib.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/ethernet/intel/idpf/idpf_lib.c b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > index 131a8121839bd..7af4214ec44de 100644
> > --- a/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > +++ b/drivers/net/ethernet/intel/idpf/idpf_lib.c
> > @@ -1308,8 +1308,10 @@ static struct idpf_vport *idpf_vport_alloc(struct idpf_adapter *adapter,
> >
> >  free_rss_key:
> >         kfree(rss_data->rss_key);
> > +       rss_data->rss_key = NULL;
> >  free_vector_idxs:
> >         kfree(vport->q_vector_idxs);
> > +       vport->q_vector_idxs = NULL;
>
> vport is freed right after this line.
>
> vport->q_vector_idxs content is not relevant.
>
> If anything tries to deref vport->any_field ater at this point, there
> is another bug. KASAN might help.

Thank you Eric! I realized this after this patch and have sent out a
v2 patch with this line removed as well.

>
> >  free_vport:
> >         kfree(vport);
> >
> > --
> > 2.52.0.457.g6b5491de43-goog
> >